Fast Protocols for Characterizing Antibody-Peptide Binding.

Microarray assay formats gained popularity in the 1990s, first implemented in DNA-based arrays but later adopted for use with proteins, namely antibodies, peptides, low molecular weight (LMW) molecules, such as lipids, and even tissues. In nucleic acid-based affinity assays and arrays, but not in protein or peptide arrays, the specificity and affinity of complementary strand interactions can be deduced from or adjusted through modifications to the nucleotide sequence. Arrays of LMW molecules are characterized by largely uniform but low binding affinities. Multiplexed protein-based affinity assays, such as microarrays, might present an additional challenge due to heterogeneity of antigen properties and of their binding affinities. The use of peptides instead of proteins reduces physical heterogeneity of these reagents through either the widened peptide selection options or rational sequence engineering. However, rational engineering of binding affinities remains an unmet need, and peptide-binding affinities to the respective antipeptide antibodies could vary by orders of magnitude. Hence, multiplexing of such assays by using a microarray format and data analysis and interpretation requires some knowledge of their binding affinities. Low-throughput binding assays to characterize such peptide-antipeptide antibodies interactions are widely available, but scaling-up of traditional protein- and peptide-binding assays might present practical challenges. Here, we describe fast label-free practical approach especially suitable for estimating peptide-binding affinities. The method in question relies on commercially available biolayer interferometry-based equipment with a protocol which can be easily scaled-up, subject to user needs and equipment availability.

Development of Emission Factors for Polypropylene Processing.

Emission factors for selected volatile organic compounds and particulate emissions were developed during extrusion of commercial grades of propylene homopolymers and copolymers with ethylene. A small commercial extruder was used. Polymer melt temperatures ranged from 400 to 605 °F. However, temperatures in excess of 510 °F for polypropylene are considered extreme. Temperatures as high as 605 °F are only used for very specialized applications, for example, melt-blown fibers. Therefore, use of this data should be matched with the resin manufacturers' recommendations. An emission factor was calculated for each substance measured and reported as pounds released to the atmosphere per million pounds of polymer processed [ppm (wt/wt)]. Based on production volumes, these emission factors can be used by processors to estimate emission quantities from polypropylene extrusion operations that are similar to the resins and the conditions used in this study.

Development of Emission Factors for Ethylene-Vinyl Acetate and Ethylene-Methyl Acrylate Copolymer Processing.

Emission factors for selected volatile organic compounds (VOCs) and particulate emissions were developed over a range of temperatures during extrusion of three mixtures of ethylene-vinyl acetate (EVA) copolymers and two mixtures of ethylene-methyl acrylate (EMA) copolymers. A mixture of low-density polyethylene (LDPE) resins was used as a control. EVAs with 9, 18, and 28% vinyl acetate (VA) were used. The EMA mixtures were both 20% methyl acrylate. A small commercial extruder was used. Polymer melt temperatures were run at 340 °F for LDPE and both 18 and 28% EVAs. The 9% EVA mixture was extruded at 435 °F melt temperature. The EMA mixtures were extruded at 350 and 565 °F melt temperatures. An emission rate for each substance was calculated, measured, and reported as pounds released to the atmosphere per million pounds of polymer processed [ppm (wt/wt)]. Based on production volumes, these emission factors can be used by processors to estimate emission quantities from EVA and EMA extrusion operations that are similar to the resins and the conditions used in the study.

Development of Emission Factors for Polyethylene Processing.

Emission factors for selected volatile organic and particulate emissions were developed over a range of temperatures during extrusion of polyethylene resins. A pilot scale extruder was used. Polymer melt temperatures ranged from 500 °F to 600 °F for low density polyethylene (LDPE), 355 °F to 500 °F for linear low density polyethylene (LLDPE), and 380 °F to 430 °F for high density polyethylene (HOPE). An emission factor was calculated for each substance measured and reported as pounds released to the atmosphere per million pounds of polymer processed (ppm[wt/wt]). Based on production volumes, these emission factors can be used by processors to estimate emissions from polyethylene extrusion operations that are similar to the conditions used in this study.